still i state, my only (but fatal!) blunder was 36.Kg2. i can't recall what was on my mind in that very moment (deep dark emptyness, for sure).
so, my answer : the reason was ... a momentary lapse of concentration. the game was great, otherwise.
thx
Nice game with alot of inaccuracies though.
Surprising analysis; please mention one or two to help improve our skills?